Doctors that perform bone graft procedures are commonly orthopaedic surgeons, otolaryngology head and neck surgeons, neurosurgeons, craniofacial surgeons, oral and maxillofacial surgeons, periodontists and dentists. Surgeons use bone grafts to repair and rebuild diseased bones in the jaws, spine, hips, knees and other bones and joints.
Over 500,000 bone graft procedures are performed in the United States each year. The estimate cost of these operations approaches US$2.5 billion per year, and millions more world wide. At least 250,000 spinal fusions are performed in the United States each year, nearly all requiring implantation of bone graft material. The preferred technique for most of these operations is the transplantation of structured or morcellized autogenous corticocancellous bone from the iliac crest. Further, because of the increasing frequency of spinal fusion surgery during the 1990's, arthrodesis of the spine has become the most common reason for autogenous bone graft harvest. Spinal fusion is the joining or fusing of one or more vertebrae to reduce pain and stabilize the spine. During spinal fusion, a wide variety of implants, screws and cages may be used to enhance the fusion. However the fusion is only considered successful when the bones grow together biologically to form a solid mass. This fused connection is primarily achieved by the incorporation of a bone graft.
Another most common use of bone grafting is in the application of dental implants for the jaws, in order to restore the edentulous area of a missing tooth. Dental implants have increased exponentially in popularity over the past fifteen years, contributing to the significant increase in demand for bone grafting in the jaws, and this trend is projected to continue in the future. As for cleft palates, the obstructed airway which often results from repair of complete clefts is a source of upper respiratory tract infections, sinusitis and otitis media leading to poor physique, deafness, bronchitis, and other ailments besides handicapping the individual's exercise tolerance for life. It is extremely difficult to correct this by operations on the soft tissues alone despite the multiplicity of ingenious techniques. The expansion of the maxilla (palate) achieves this more completely and with more certainty and the operation is worth doing for this purpose alone. Rapid expansion of the collapsed maxilla is performed with orthodontic appliances, followed by bone grafting which provides and ensures its permanent stability, and reconstructing the defects. The main bone graft is best taken from the inner table of the ilium, and match stick bone pegs are included alongside to reinforce stability of the main graft.
The most critical problem during a dental implant placement is the reduced amount of available bone to support it and to achieve the necessary initial stability for osseointegration to occur. In many cases, the jawbones have been so severely destroyed by gum disease that the minimum available bone height and width required for accommodating the dental implant is often absent. Without bone grafting procedures to provide additional bone, many dental implant placements are not possible.
Bovine bone, i.e. cow bone, has become very popular, and commercially successful. It comes in particulate form and it is mixed with saline for the grafting of bony defects, or for grafting into the floor of the maxillary sinus to accommodate the dental implant. However, there are two problems associated with the use of animal bone. Firstly, bovine bone, like all commercial bone products, requires seven to twelve months to sufficiently consolidate to receive a dental implant. It has no living osteogenic cells, and the quality does not compare to the patient's natural vibrant and resilient bone, which when harvested, often contains healthy blood vessels, contributing to the ideal.
Secondly, there are concerns from the patients' point of view that it is of animal bone, and opens the risk of acquiring mad cow disease. There are other choice forms of bone, alloplasts like ceramic grafts, or hydroxyapatite and tricalcium phosphate, bioglass, etc. and so on, but they are mostly in particulate form and cannot provide the solid block of bone for tangible use. In addition, these are very expensive materials.
Allografts are bone tissues taken from human cadavers, and although these are treated by tissue freezing, freeze-drying, gamma radiation, electron beam radiation, ethylene oxide, etc., the risk of disease transmission is not completely removed; as in HIV, Hepatitis B and Hepatitis C, and other various pathogens. A case of death has been reported, in particular, a patient died of infection caused by Clostridium Sordellii within four days of the surgery, in November 2001, prompting investigations which revealed more cases of allograft-related infections.
Autogenous or autologous bone is the patient's own bone. In general, most patients prefer this prime choice. It is the ideal bone to use for bone augmentation in oral surgery, implant dentistry, orthopaedic surgery and wherever bone grafting is required in the human body. Autogenous bone is always regarded as the gold standard, and superior to all other alternative non-autogenous bone products. The greatest advantage is that autogenous bone provides osteogenic cells for phase I bone formation, and no immunologic response occurs. In fact autogenous bone is highly osteogenic and best fulfills the dental-grafting requirements of providing a scaffold for bone regeneration. In addition, it saves time. Whereas all commercial bone products require seven to twelve months to consolidate and fuse with the native recipient bone, autogenous bone does so in three months. Henceforth the provision of teeth onto dental implants into this bone can be accomplished in a much shorter time frame. In the operator's point of view, the time frame is an important factor, and would avoid the use of all such bone products as these would impose a significant prolonged time frame for the treatment case to be completed, and in many instances, up to a year. However, the complexity and risks of harvesting the patient's own bone currently render most dental operators unable to proceed at this point.
Typically autogenous bone grafts are taken from the pelvis or iliac crest. All bone requires blood supply to the transported site and bone grafts which already contain blood vessels is the ideal. Autogenous bone in solid block form is ideal for this reason, and it also contains bone morphogenetic proteins (BMP's), but in fact, autogenous bone possesses all of the characteristics required for new bone growth, namely, osteoconductivity, osteogenicity, and osteoinductivity.
The current procedure imposes the inevitable need for a second operation at a donor site, and with prior art tool, it is a traumatic and tedious process. Specialist oral surgeons are capable of harvesting autogenous bone from chosen donor sites in the patient's mouth. However the tedious and traumatic nature of the task also involves great risks of complications, being an invasive and often destructive process using prior art. Prior art tools include bone saws, bone drills, hammers and chisels, elevators to peel and lift out the bone block, and the trephine drill to define circular shapes of bone blocks which must subsequently be procured by free hand, with skill, using an array of various elevators.
Whereas the prior art standard trephine drill provides a roof and walls to confine the bone stud it creates, it does not provide a floor base to fully contain it, to support it and hence to harvest it.
As access is difficult for such a task, extensive incisions for large openings at the surgical site are often necessary, contributing to an increased size of the donor wound, and subsequent associated morbidity. With prior art bone harvesting tools, very often the tediously harvested block of bone has to be dramatically reduced and reshaped in order to fit the deficient bony site it is destined for, and bone is wasted in the process. Autogenous bone grafting has indeed excellent fusion rates and has become the gold standard by which all other biologics are measured. Many surgeons prefer autogenous bone grafts because there is no risk of the body rejecting the graft since it came from the patient's own body. The current disadvantage of autogenous bone grafting in orthopaedic surgery is the need for an additional operation which is currently traumatic. The pain and soreness can often last well after the surgery is healed, and there are possible complications such as increased blood loss and prolonged time in the operating room in about 10% to 35% of patients, and varying in severity in these cases, with the use of prior art.
As autogenous bone harvesting is associated with such untoward morbidities, and the use of alternatives of biological non-autogenous bone blocks have been reported to produce sporadic results of success, there exists a need to provide a bone harvesting device in which the aforesaid shortcomings are mitigated, or at least to provide a useful alternative to the trade and public.